[PATCH 0/5] watchdog_hld cleanup and async model for arm64

From: Pingfan Liu
Date: Tue Sep 14 2021 - 23:51:26 EST


hard lockup detector is helpful to diagnose unpaired irq enable/disable.
Sumit has tried with a series, and the last one is V5 [1].
Since it lasts a long time without any update, I takes a retry, which
addresses the delay intialization of watchdog_hld.

There is an obstacle to integrate arm64 hw perf event into watchdog_hld.
When lockup_detector_init()->watchdog_nmi_probe(), on arm64, PMU is not
ready until device_initcall(armv8_pmu_driver_init). And it is deeply
integrated with the driver model and cpuhp. Hence it is hard to push
the initialization of armv8_pmu_driver_init() before smp_init().

But it is easy to take an opposite approach by enabling watchdog_hld to
get the capability of PMU async. The async model is achieved by
introducing an extra parameter notifier of watchdog_nmi_probe().

In this series, [1-2/5] are trivial cleanup. [3-5/5] is for this async
model.

[1]: http://lore.kernel.org/linux-arm-kernel/1610712101-14929-1-git-send-email-sumit.garg@xxxxxxxxxx

Cc: Sumit Garg <sumit.garg@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Julien Thierry <jthierry@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Wang Qing <wangqing@xxxxxxxx>
Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Cc: Santosh Sivaraj <santosh@xxxxxxxxxx>
To: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
To: linux-kernel@xxxxxxxxxxxxxxx


Pingfan Liu (5):
kernel/watchdog: remove useless WATCHDOG_DEFAULT
kernel/watchdog_hld: clarify the condition in
hardlockup_detector_event_create()
kernel/watchdog: adapt the watchdog_hld interface for async model
kernel/watchdog_hld: simplify the detecting of hld watchdog
arm64/watchdog_hld: enable hard lockup on arm64 platform

arch/arm64/Kconfig | 3 ++
arch/arm64/include/asm/perf_event.h | 5 ++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/perf_event.c | 14 ++++-
arch/arm64/kernel/watchdog_hld.c | 83 +++++++++++++++++++++++++++++
drivers/perf/arm_pmu.c | 5 ++
include/linux/nmi.h | 20 ++++---
kernel/watchdog.c | 69 ++++++++++++++++++------
kernel/watchdog_hld.c | 26 +++------
9 files changed, 181 insertions(+), 45 deletions(-)
create mode 100644 arch/arm64/kernel/watchdog_hld.c

--
2.31.1